It sounds like you're making cheese popcorn for retail sale. I'm not familiar with the types of toppings used for this purpose and would suggest you talk with your suppliers. They can also give you storage tips.

If you want to make gourmet cheese popcorn for personal consumption, you can try brewers yeast (also known as nutritional yeast), which gives popcorn a cheesy flavor without the fat or calories. Storing in an airtight container helps keep popcorn fresh, but it's always best eaten immediately. Freshly grated parmesan cheese tastes great, but would be best eaten shortly after you've made it.